Condition responsive apparatus



July 24, 1962 R. P. ALLEY ET AL CONDITION RESPONSIVE APPARATUS FiledSept. 21, 1960 Inventors: Robert. P. Alley, Robert B. Wilkerson Th eirAttorney.

United States Patent Gfifice 3,046,449 Patented July 24, 1 962 3,46,4-t9CONDITIQN RESlPQNSlVE APPARATUS Robert I. Alley, hirley, and Robert B.Wilkerson, Bloomington, Ill., assignors to General Electric ilolnpany, acorporation of New York Filed Sept. 21, race, Ser. No. 57,459

' 11 Claims. (Cl. 3l75) This invention relates to condition responsiveapparatus and more particularly to apparatus responsive to a relativemotion of a movable member.

It is frequently desirable to provide means for indicating when amovable body, such, for example, as the rotor of an electric motor, isin motion and when it is at rest. In addition, it is often desirable toprovide means for indicating a given condition of movement of such amovable body, such as, means to indicate when such a body exceeds apredetermined rate of movement. in the past, numerous different types ofapparatus have been developed for indicating given conditions obtainedby a movable member. For example, various inertial devices, such ascentrifugal switches, have been coupled to be driven by a movable memberthat is to be monitored to provide an indicating function.

A centrifugal switch of the mechanical type invariably requires somesort of sliding electrical connection such as slip rings to makeconnections between the rotatable parts of the switch and the externalcircuit in which it functions. Furthermore there are the usual problemsencountered in movable contact devices such as contact contamination,wear and arc erosion, problems aggravated by the industrial environmentsin which the centrifugal switch is often required to function.Centrifugal switches of the mercury type may be classified in two broadcategories. First there are those in which the electrical contactsrotate into and out of contact with a mercury pool. Then there are thosehaving stationary contacts with the mercury being spun, poured orspilled onto the contacts. The first of these two types of centrifugalmercury switches requires slip ring structures or the like, while theother requires penetration of the mercury enclosure through a bearingarrangement or something similar to bring into the enclosure therequired electrical connections. Each of these types of centrifugalswitches, of course, has its advantages as well as its disadvantages.

It is a general object of this invention to provide a uniquecondition-responsive switch which combines many of the best features ofits predecessors while avoiding many of their disadvantages.

More specifically, an object of this invention is to provide rotationresponsive apparatus in the nature of a 'switch,.which has no physicalcontacts as such, which requires no slip rings or other slidingelectrical connections, and in which the sensing function is a result ofeffects which take place entirely within a sealed enclosure with out thenecessity of ,physical penetration of the enclosure to bring inelectrical connections.

A stillfurther object of the invention is to provide a motion-sensingapparatus in which a change is induced in impedance of a'reactivewinding on a magnetic core structure in response to the movement of anobject whose motion is being monitored, the change in impedanceproviding a sensing function.

Briefly stated, in accordance with one preferred embodiment of theinvention, a magnetizable core structure is provided having anelectrical winding wound thereon in the nature of a primary transformerWinding to induce a changing magnetic flux in the core structure. Ahollow annulus, formed from electrical insulating material, andpartially filled with an electrically conductive liquid is positionedaround a portion of the core structure and is rotatably journaledthereon. Drive means are provided to couple the annulus to a movablemember, the motion of which is to be monitored, and the drive means iseffective to rotate the annulus when the monitored member is moved. Whensuch movement of the monitored member occurs and exceeds a predeterminedvelocity, the electrically conductive liquid is thrown by a combinationof forces including viscous drag and centrifugal force over the outerwall of the annulus and is thereby forced entirely around the annulus toform an electrically conductive path or shorted-turn, which through thetransformer effect reduces the impedance of the electrical winding onthe core structure. Thus, the alternating current impedance of theprimary-type winding is markedly decreased. Suitable control orindicating means responsive to the change in the impedance of thewinding are provided to perform desirable types of indicating or controlfunction in response to variations in the current passing through thewinding.

Further details of the invention as well as additional objects andadvantageswill become apparent from the description that follows takenin conjunction with the drawings in which:

FIGURE 1 is a perspective view, partly, in cross-section, of anindicating or control apparatus constructed in accordance with theteachings of the invention;

FIGURE 2 is a perspective view, taken in cross-section along the plane22 of FIGURE 1;

FIGURE 3 is a schematic circuit diagram of an indicating system arrangedin accordance with the teachings of the invention;

FIGURE 4 is a perspective, fragmentary, view illustrating schematicallya second form of condition responsive apparatus constructed inaccordance with the teachings of the invention; and

FIGURE 5 is a fragmentary view, taken in cross-section along the plane55 of FIGURE 4.

With reference to FIGURES 1 and 2 of the drawings, it will be seen thatin a first embodiment of the invention a magnetizable core structure 1is supported on brackets 2 and 3 by any suitable means (notillustrated). In the embodiment shown, the magnetizable core member 1comprises a plurality of E-shaped, iron laminations bonded together byany conventional means toform a three-legged magnetic core structure.However, it should be understood that the particular material orconfiguration of the magnetizable member 1 may be varied considerablyfrom that shown. The core structure should preferably have a relativelyhigh permeance to the passage of magnetic flux there/through. Themagnetizable core structure 1 has a central leg 4 (FIGURE 2) on whichthe coil or primary winding 5 is positioned. The winding 5 shouldcomprise a number of turns of an electrical conductor preferablyinsulated from the core structure by the coil form 6 of insulatingmaterial. The winding 5 is provided to afford means for producing analternating magnetic field and thus inducing a changing magnetic flux inthe core structure 1. For this purpose the winding 5 is provided withsuitable electrical connections for energizing the winding from analternating current source.

It will become apparent as the description of this embodiment proceedsthat a reduction in the impedance of the winding 5 to the passage ofalternating electric c rents therethrough, due to the formation of theshorted turn on the core structure, is utilized to provide desirablecontrol or indicating functions In order to effect such a variation inthe impedance of the Winding 5, a hollow annulus 7 of insulatingmaterial, rotatably supported in position on the central leg 4 of thecore structure, is partially filled with an electrically conductiveliquid 8 such as mercury. Referring particularly to FIGURE 2, it will beseen that the hollow annulus 7 resembles a toroid having cylindricalouter and inner walls 7a and 7b re- D spectively joined by side walls,one of which, 7c, is visible in FIGURE 1.

As will be seen by referring to FIGURE 2, the predetermined amount ofthe fluid 8 disposed within the annulus is insufiicient to form anelectrically conductive path that completely encircles the core -legportion 4 when the annulus is in a substantially vertical plane and atrest "as shown. The annulus is formed of an insulating material and issupported on the core leg portion 4 by a non-shorting circular journal 9to provide an insulating bearing surface for the annulus. The journal ispreferably of sintered bronze split on one side at 9a but might also beof nylon or the like. It will be seen that if the fluid 8 extendedentirely around the core 4 so as to completely encircle it, thestructure would resemble an electrical transformer having a shorted-turnfor a secondary winding. The electrical impedance of the primary winding5 would naturally be very low with the secondary winding in the form ofa shorted turn.

In order to provide means for moving the liquid 8 under the action ofviscous friction or centrifugal forces to completely encircle thecentral core leg 4, the annulus 7, rotatably supported with respect tothe core leg portion 4 by the outer bearing surface of journal 9, isprovided with gear teeth it} formed around the outer periphery thereof.The gear teeth 10' are disposed in driving engagement with a second gear11 which is rigidly mounted on a shalt 12 rotatably supported in thebrackets 2 and 3. The shaft 12 may be coupled by any suitable means to amovable member, the motion of which is to be monitored by u theapparatus shown; however, no such connections have been specificallyillustrated since it will be readily understood that such connectionsmay take any conventional form so long as they impart a rotary movementto the annulus 7 in response to movement of the monitored member.

The operation of the first illustrated embodiment of the invention willbe readily understood when it is appreciated that in its operativecondition the primary winding 5 is energized by applying an alternatingpotential thereto to induce a magnetic flux in the magnetizable member 1and the core 4, and that the shaft 12 is drivingly connected to amovable member the motion of which is to be monitored. When themonitored member is stationary, the shaft 12 does not rotate and, thus,the electrically conductive fluid does not completely encircle the core4. Therefore, the electrical impedance of the primary winding 5 will beat a relatively high value. When the monitored movable member starts tomove, the shaft 12 and its associated gear 11 will rotate and, thus,drive the gear 10 and the annulus 7 to which it is mounted thereby torotate the annulus 7. Rotation of the annulus 7 causes the fluid 8 to beforced around the core leg portion 4, due to the inherent frictionbetween the fluid 8 and the walls 7a and 7b of the annulus 7. When theangular velocity exceeds a predetermined minimum velocity, the rate ofliquid flow over the top of the annulus becomes sufficient to completethe electrically conducting path around core leg 4. At higher velocitiescentrifugal force distributes the fluid 8 uniformly around the outerwall of the annulus 7 thereby forming a short-circuited secondarywinding turn entirely around the central core leg 4. When theelectrically conductive fluid 8 thus forms a continuouscurrent-conducting path encircling the core leg portion 4, the impedanceof the primary winding 5 decreases markedly. By making use of thiseffect, the apparatus shown in FIGURES l and 2 may be utilized toperform indicating or control functions.

In FIGURE 3 there is schematically depicted an indicating systemconstructed in accordance with the invention. This system employs as oneof its components a unit of the nature described in connection withFIGS. 1 and 2 of the drawings and designated in FIGURE 3 as the unit 13.The unit 13 thus comprises a magnetic core structure 4 inductivelycoupling a primary winding 5 with an electrically conductive fluid 8capable of forming a shorted turn about the core structure. A solenoidor relay Winding 14 is electrically connected in series with the winding5 to actuate a double-pole switch 15 having stationary contacts 15a and15b. In order to provide an indicating function, the contacts 15a and15]) are connected respectively to indicating lamps 16 and 17, the othersides of the lamps 16 and 17 being connected through conductors 18 and19 to one side of a source of electrical energy represented by terminal20, whereas the conductor 21 is connected between the other side of thissource of energy represented by terminal 22 and the movable arm ofswitch 15. The winding 5 and the solenoid 14 are also connected throughelectrical connectors 23 and 24 to a suitable source of alternatingcurrent potential represented byterminals 25. The movable switch arm 15is normally biased, as shown, towards contact 15a, so that when thesolenoid 14 is deenergized an electrical circuit is completed throughlamp 16 and the conductor 13 to both sides of the source of power, thus,energizing the indicating lamp 16 to indicate this condition.

When the conductive liquid, shown schematically at 8 in FIGURE 3, formsa shorted turn, it decreases the impedance of the primary winding 5through its inductive relation with the core leg portion 4- and winding5 thereby increasing the operating current to solenoid 14. Theelectrical impedance values of the winding 5 and the currentresponsivesolenoid 14 are chosen such that the solenoid 14 will drop out when theimpedance of coil 5 is high due to an open circuit condition of thefluid 3. When the movement of the monitored equipment causes thecompletion of an electric path through the liquid 8, the impedance ofwinding 5 will be reduced and allow more current to flow throughsolenoid 14 so it will pick up and move the arm of switch 15 fromcontact 15a to contact 15b. The primary winding 5 therefore performs aswitching function somewhat similar to that performed by a magneticamplifier gate Winding. Of course, when the switch 15 is connected tocontact 15b the lamp 17 is energized to indicate this condition.

Although we have selected a relay operating circuit as an example of theindicating or control operations which can be performed by the practiceof this invention, it should at this point be obvious that the gatingeffect of the primary winding may be employed to good advantage not onlyin electromagnetic circuits but also in electronic and magneticamplifier-type circuits. Furthermore, the controlled element might be,instead of indicating lamps as shown in FIGURE 3, a motor or other loaddevice employed to exert a corrective or control eifect upon thecondition monitored or to perform a simpl work operation in response tothe condition. There are, in fact, many different ways in which thepresent invention may be employed.

Another type of condition-responsive apparatus embodying the principlesof this invention is shown in FIG- URES 4 and 5. There, a magnetizablecore structure 30 is provided with an energizing winding 31 encirclingits central leg and connected across a source of alternating currentpotential represented by terminals 32 to induce a changing magnetic fluxin the core structure. The core structure is three-legged with one legportion 33 encircled by a hollow annulus 34 having gear teeth 35 formedon an external surface. The gear teeth of the annulus, which issupported by hearing means not illustrated for rotation about core leg33, are engaged to be driven by a gear 36 coupled to a rotatable shaft37 the relative motion of which is to be monitored. The annulus 34 isagain formed of an insulating material partially filled with anelectrically conductive liquid 38 (FIGURE 5), preferably mercury, but isdisposed in a horizontal plane rather than a vertical one. Theliquid-filled annulus provides means for forming an electricallyconductive path or shorted turn encircling the leg 33 of themagnetizable core structure when the annulus is rotated with apredetermined minimum angular velocity.

In FIGURE 5, it will be seen that the interior of the horizontallymounted annulus 34 utilized in this second embodiment of the inventiondiffers from the annulus 7 shown in the previously discussed embodimentin that within the interior passageway formed in the annulus is disposedat least one vertical partition 39- of insulating material extending alittle higher than the surface of the liquid conductor. When the annulusis at rest, this partition 39 interrupts the peripheral continuity ofthe liquid conductor 35 and prevents the formation of a continuouselectrically conducting path encircling the leg 33. However, when theannulus is rotated, the liquid is thrown up and out by centrifugal forcealong the sloped base wall 40 toward the outer peripheral wall of theannulus until it flows over the partition 39, joins and forms acontinuous electrically conductive path or shorted turn around theentire inner surface of the annulus.

In this embodiment, shown in FIGURE 4, one of the legs of themagnetizable core structure 30 is mounted as a movable magnetic armature41, being fastened by a hinge 42 and carrying a contact actuating arm43. The arm 43 is provided with a pair of electrical contact bridgingmembers 44 and 45 mounted by appropriate means upon the end of' arm 43.Two pairs of circuit-controlling stationary contacts 46 and 47 aredisposed to cooperate with the contact bridging members 44 and 45respectively, and may be connected to an indicating or control circuitto perform any of a variety of predetermined functions when theirassociated circuits are selectively completed by movement of armature41.

in the operation of the apparatus shown in FIGURE 4, the alternatingcurrent potential connected to terminals 32 of the energization winding31 induces circulating fluxes in the core structure which favor theportion of the core structure including leg 33, because of the air gapswith lowenpermeance through which the flux must pass to traverse thearmature 41. With the annulus at rest, therefore, only a weak leakageflux will be available to exert a force onthe armature 41 by theadjacent portions of the core structure, a force insufiicient to attractthe armature 41 to the basic core structure. When, due to rotation ofthe shaft 37 and annulus 34, a shorted turn is formed about leg 33 ofthe core, the transformer eifect immediately reduces the impedance ofwinding 31 causing it to supply more ampere turns. As a consequence, theincreased magnetomotive force generated within the core structure bywinding 31 gives rise to a larger leakage flux which exerts on armature41 an increased attractive force. Under this stronger force ofattraction the armature 41 closes against the basic core structure, andin doing so, opens contacts 47 and closes contacts 46. When the shortedturn is interrupted due to the slowing down or stopping of rotation ofthe annulus 34, and the primary ampere turns supplied by winding 31decrease the armature 41 will return to the position shown in FIGURE 4due to the force of gravity or other suitable biasing means. In doing socontacts 45 will open and contacts 47 will close.

it should be understood that in the embodiment of the invention shown inFIGURE 4 the armature 41 need not be hinged directly on the basic corestructure but need only be movably mounted in magnetic relationtherewith to accomplish the desired operational features. Furthermore,while no particular mechanical arrangement for rotatably mounting theannulus 7 on the leg 4 of magnetizable member 1 has been shown, anysuitable journal arrangement which does not form an already completeshorted turn about the core structure may be utilized without departingfrom the principles of this invention. For example, a journal similar tothe one shown in FIG- URE 2 could be employed for this purpose.

While particular illustrative embodiments of the invention forindicating or controlling various predetermined functions have beenillustrated and described, and certain modifications have beensuggested, it will be obvious to those skilled in the art that variousother modifications may be made without departing from the invention inits broader aspects. Therefore, it is intended in the following appendedclaims to encompass all such modifications as fall within the truespirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

l. Condition responsive apparatus comprising: a magnetic core structure;a primary winding inductively associated with said core structure forconnection to a source of alternating current potential to draw currenttherefrom for inducing alternating magnetic fluxes in said corestructure; means for forming a shorted turn secondary Winding inresponse to a variable condition to be monitored including a hollowannulus encircling a portion of said core structure and formed at leastin part of insulating material to prevent the circulation of electricalcurrents therein, a conductive liquid partially filling said annulus toextend less than the total distance around said core structure when saidannulus is at rest, and means responsive to said variable condition forspinning said annulus on its axis thereby to force said conductiveliquid to form a shorted turn about said core structure; and meansresponsive to variations in current drawn by said primary winding forperforming an operation depending on said variable condition.

2. In combination: a magnetically permeable core structure; meansincluding an electrical winding for inducing periodically varyingmagnetic fluxes in said core structure; a hollow annulus of electricallyinsulating material encircling a portion of said core structure andmounted for rotation thereabout; an electrically conductive liquidpartially filling said annulus and extending less than the entiredistance around the annulus when the annulus is at rest, said conductiveliquid being forced to completely encircle said portion of said corestructure when said annulus is rotated with a predetermined minimumangular velocity, whereby the impedance of said electrical winding isreduced when said conductive liquid forms a shorted turn; means forrotating said annulus at a velocity in accordance with a variablecondition; and means responsive to a reduction in the impedance of saidelectrical winding for performing a responsive operation.

3. In combination: a magnetically permeable core structure; meansincluding an electrical winding inductively associated with said corestructure for inducing periodically varying magnetic fluxes in said corestructure; a body of electrically conductive liquid normally extendingonly part way around a portion of said core structure; means operatingin response to a variable condition for forming said conductive liquidinto a shorted turn completely encircling a portion of said magneticcore structure; and means responsive to a reduction in impedance of saidelectrical winding for performing an operation dependent on saidvariable condition.

4. Condition responsive apparatus comprising: an electric currentconductor wound to form a coil having an aperture extending axiallytherethrough; a hollow annulus of insulating material, an electricallyconductive liquid partially filling said annulus and disposed ininductive relation with said coil; means responsive to a variablecondition for selectively causing said conductive liquid to extendcompletely about the circumference of said annulus to provide a lowimpedance path for electric current in inductive relationship with saidcoil, said low impedance path being effective through its inductiverelation with said coil to lower the impedance of said coil to thepassage of alternating electric current therethrough.

5. Condition responsive apparatus as defined in claim 4 in which themeans for selectively causing said conductive fluid to extend completelyabout the circumference of said annulus includes structure mounting saidannulus for rotation about its axis and means responsive to saidvariable condition for rotating said annulus thereby to form under theaction of centrifugal and viscous forces an electrically conductive pathof said conductive liquid extending completely about the circumferenceof said annulus.

6. Condition responsive apparatus as defined in claim including amagnetic core structure having portions thereof disposed respectively inthe axial apertures of said coil and said annulus.

7. Condition responsive apparatus comprising: a magnetic core structure;a coil surrounding a portion of said core structure for connection to asource of alternating current potential; a hollow annulus of insulatingmaterial 'rotatably positioned to surround a portion of said core;

an electrically conductive liquid partially filling said an nulus andextending less than the total distance around the annulus when theannulus is at rest, said annulus being adapted to extend said conductiveliquid completely around the annulus to form an electrically shortedturn around a portion of said core structure when said annulus isrotated; and means for rotating said annulus in response to a variablecondition, whereby a change in impedance in said coil is effected byrotation of said annulus.

8. Condition responsive means comprising: a magnetic core structure; aprimary winding inductively associated with said core structure; anenergization circuit including said primary winding for connection to asource of periodically varying potential; and means for varying theimpedance of said primary Winding to control the current in saidenergization circuit including a body of electrically conductive liquidnormally extending only a part of the distance around a portion of saidcore structure, and means operating in response to a variable conditionfor forming said conductive liquid into a shorted turn completelyencircling a portion of said magnetic core structure and inductivelycoupled to said primary winding.

9. Condition responsive means comprising: a magnetic core structure; aprimary winding wound on said core structure; a load circuit includingsaid primary winding for connection to a source of periodically varyingpotential; and means for varying the impedance of said primary windingto control the electrical energy in said load circuit including a hollowannulus of electrically insulating material encircling a portion of saidcore structure and mounted for rotation thereabout; an electricallyconductive liquid partially filling said annulus and extending partlyaround the annulus when the annulus is at rest, said annulus beingadapted to effect the extension of said conductive liquid completelyaround the annulus by centrifugal and viscous forces to form anelectrically shorted turn around said core when said annulus is rotated,and means for rotating said annulus in response to a variable condition.

10. Condition responsive apparatus comprising: magnetic field-producingmeans including a magnetic core structure and an electrical windinginductively associated therewith for connection to a source ofalternating current potential; a magnetic armature movably supported inproximity to said magnetic field-producing means for movement inresponse to the magnetic field produced by said magnetic field-producingmeans; means actuated by the movement of said magnetic armature forperforming a responsive function; and a selectively rotatable hollowannulus partially filled with an electrically conductive liquid andencircling a portion of said core structure for selectively varying saidmagnetic field to effect movement of said magnetizablemember, saidelectrically conductive liquid being confined within said annulus toform an electrically conductive path around said annulus only when saidannulus is rotated with a predetermined minimum angular velocity, theformation of said conductive path being effective to increase the ampereturns supplied by said winding thereby to vary the field produced bysaid field producing means.

11. Condition responsive apparatus as defined in claim 10 in which saidmagnetic field-producing means includes a multi-legged magnetic corestructure in which the distribution and magnitude of magnetic fluxproduced by said electrical winding is varied by the formation of saidelectrically conductive path about the annulus and in which the movablemagnetic member responds to such changes in flux distribution andmagnitude.

Fielden Jan. 28, 1958 Melas Oct. 10, 1944

